A heald frame comprises a square framework constructed to have framestaves acting as upper and lower frames coupled to side stays acting as left and right frames. The heald frame is equipped to support the warp ends of a multiplicity of healds. Carrier rods are fixed to the upper and lower framestaves respectively, and the healds, span the space between the upper and lower carrier rods. Thus, the heald frame, equipped with a multiplicity of healds, is incorporated into a loom and, then is vertically moved in a reciprocal manner. The conventional loom is operated at a very high speed which moves the heald frame up and down at an equivalent high speed. As a result, severe inertial forces act upon the heald frame, causing deformation and vibration in the frame.
In order to cope with the deformation and vibration in the frame, conventional frames are provided with appropriate clearances between coupling ends of the heald frame and its carrier rods. If these clearances are made either too large or too small the loom will not function properly. If the clearance is large, a severe swinging of the healds from the high speed movement of the heald frame may cause the warp ends to be cut or give rise to fuzzing of the woven cloth. If the clearance is too small, deformation of the frame may result in broken healds.
The conventional heald frame which employs a fixed coupling system makes it difficult to maintain appropriate clearances. Experience indicates that even if appropriate clearances are provided at the design stage, errors in assembling the heald frame lead to inadequate clearances. Further, long-term usage of such frames may cause the coupled ends of the frames to become so worn that clearance amount is enlarged to a point that the frame does not function properly. Furthermore, appropriate clearances are subject to the conditions under which the weaving process is undertaken. Thus, the appropriate clearance also depends upon the thickness of the yarn or operation speed of the loom. For this reason, no matter how the clearance amount is set at the design stage of making the heald frame, the frame's usage may sometimes result in the need for different clearances.
Thus, although it is important that an appropriate clearance between the coupling ends of the heald frame and the carrier rod be maintained, the conventional heald frame does not possess any means of correcting the clearance amount because the upper and lower framestaves are fixed so as to maintain a chosen distance between the upper and lower carrier rods.